Resolving The Online-Offline Attribution Challenge With DNI

It is a classic online attribution challenge: tracking offline leads driven by online sources. Interactive agencies and digital publishers are using SEM to drive leads for national and local advertisers but aren’t getting credit for the calls generated by the programs. The solution is DNI (dynamic number insertion) technology which enables a business’ phone number […]

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It is a classic online attribution challenge: tracking offline leads driven by online sources. Interactive agencies and digital publishers are using SEM to drive leads for national and local advertisers but aren’t getting credit for the calls generated by the programs.

The solution is DNI (dynamic number insertion) technology which enables a business’ phone number appearing throughout a website to be dynamically replaced with a call tracking number indicating how the consumer arrived there. When a business receives a call from the number on the website, it can then be tracked back to the appropriate source.

DNI is critical to attribution as it helps calls bridge the online-offline gap and assures publishers and agencies are getting credit for offline inquiries driven by online sources, not to mention providing advertisers more complete visibility into their leads.

For one local search publisher, using DNI revealed that nearly 35% of Web users who were referred to the advertiser’s website through SEM strategies ­made a phone call. Without DNI in place, the advertiser may have seen the increase in calls but wouldn’t be able to link them to the SEM campaign.

In addition, the calls would have been incorrectly attributed to another source. DNI revealed key intelligence to the publisher regarding the distribution partners – who was actually delivering leads – and helped discover additional monetization opportunities for their pay per call programs.

Primary Approaches To DNI: Reverse Proxy & JavaScript

If you are not familiar with DNI, there are two primary methods: Reverse Proxy and JavaScript. As Reverse Proxy options are readily available from SEM or other third-party resellers and require little advertiser effort, it is very effective for SMBs and local advertisers that do not have sophisticated internal technology resources available to make modifications to their existing websites.

Reverse Proxy uses a cached or real time copy of an advertiser’s website to display the appropriate call tracking number based on the keyword or search engine distribution partner.

For example, a consumer who searches for a home inspector could arrive at the same home inspector website via multiple search engines – either a Google search or a Bing search. As the Reverse Proxy method utilizes copies of the website, the webpages delivered by Google and Bing would look exactly the same, except each would display a unique call tracking number.

The publisher could hone in on how each distribution partner performed via the number of resulting calls from the website visits and gain attribution for those phone leads. The same principle could be applied to keywords or combinations of keywords and search engine distribution partners.


With JavaScript, which is ideal for national advertisers as it requires some coding expertise, a snippet of JavaScript code is inserted into an advertiser’s website and links to a call tracking provider’s servers.

When a search result routes a user to the advertiser’s website, the JavaScript takes the keyword parameters used to perform the search and processes them against the predefined referring search engine and keyword triggers. The result is a series of call tracking phone number substitutions populated throughout the advertiser’s website.

Other Developments In DNI Offerings

As the use of DNI has increased, newer variations of DNI setups have surfaced – including Session-based and Sampling methods – as publishers and agencies with complex national campaigns could have thousands of search engine/keyword combinations that can be onerous to track and manage. Not all of these variations align with measurement and attribution best practices, so buyer beware.

Session-based DNI involves cycling through a set of call tracking numbers based on the user’s session, so, as an example, if using a set of 10 call tracking numbers, the 11th user would be presented with  the same number as the first when referred to the website from a tracked SEM campaign. The method uses date and time stamping to associate Web sessions to phone calls to track calls back to referring search engines and keywords.

One challenge, however, is that session-based DNI can result in data integrity issues without a 1-to-1 relationship of variable-to-phone number and can therefore skew results. As a site with high traffic periods can cycle through a set of numbers quickly, date and time stamping alone may cause calls to be attributed to the wrong search or source.

Consider a pizza delivery service on a Friday evening and how many searchers and resulting callers could overlap. Someone utilizing a phone number from a search conducted at 5:45 pm may not call until 5:56 pm, while a search at 5:48 pm may result in a call at 5:50 pm and alter the results. Similarly, a search for “pizzeria” may serve up the same call tracking number as a search for “family restaurant”.

Session-based DNI also may include pooling or sharing a set of call tracking numbers across a similar group of advertisers. While this may seem like an economical way to generate vertical market insights, say for a group of plumbers, data integrity challenges arise as overlapping data can skew performance results across different accounts.

A best practice to leverage cost-efficient DNI for large campaigns is Sampling. You don’t have to measure campaigns to the Nth degree to receive valuable insights. With Sampling, advertisers, publishers and/or agencies can achieve high quality and accurate results because there is a 1-1 tracking ratio.

Instead of simultaneously tracking all your keywords, distribution partners or combinations of the two, start by tracking the top 50 most profitable keywords to generate some relevant insights and then optimize the program for those top-priority keywords before evaluating the next grouping of keywords.

Similarly, local search publishers can do Sampling within categories of advertisers. Some providers are also offering pay-for-performance DNI options, which may be attractive for cost-effectively managing enterprise-level programs.

DNI is continuing to close the online-offline attribution gap and is a key part of any digital advertiser’s or provider’s toolkit. Not only does it ensure the proper channel receives credit for phone leads but it is also helpful in optimizing advertising programs to leverage the highest performing keywords, partners, media channels and combos.

Opinions expressed in this article are those of the guest author and not necessarily Search Engine Land. Staff authors are listed here.

About the author

Bill Dinan
Bill Dinan is president of Localogy, a not-for-profit trade association comprised of technology, marketing and media service providers and multi-location brands that help small businesses thrive in an increasingly localized world. Bringing deep expertise on how local commerce industries are evolving with new technology and business approaches, Dinan has successfully led and grown companies over the last few decades, including, Acquisio, Telmetrics and others.

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